DE69528013T2 - Management system for turbocharger control - Google Patents

Abstract

An electronic turbocharger control system for an internal combustion engine is provided to control at least one turbocharger (16) by controlling a bypass valve (40) and a wastegate (44) in response to the engine speed, engine load, ambient temperature, and the operating environment's barometric pressure wherein the turbocharger is controlled to operate within predetermined islands of efficiency on a pressure ratio versus mass airflow map thereby allowing the adaptation of one turbocharger assembly for various applications. The method and apparatus provides improved engine efficiency and increases low speed torque. <IMAGE>

Description

The invention relates to a turbocharger control and management system for maximizing the efficiency of a turbocharger and an internal combustion engine.

A turbocharger includes a compressor and a turbine. The turbine drives the compressor using exhaust energy generated by an internal combustion engine. The engine exhaust gases drive a turbine wheel in the turbocharger's turbine and are exhausted through an exhaust system. The turbine wheel drives a shaft connected to a compressor wheel in the compressor, which pressurizes intake air, previously at atmospheric pressure, causing it to flow typically through an intercooler, over a throttle valve, and into an engine intake manifold.

Controlling turbocharger output to achieve desired engine operation is a long-standing problem. Too much output can cause erratic engine operation and permanent damage to engine components. Too little output results in engine stalling, loss of power and inefficient operation.

In addition, changes in atmospheric pressure, ambient temperature and engine speed affect the overall efficiency of the turbocharger, which in turn has a direct impact on the engine's performance, output and fuel economy.

Prior to the present invention, some turbocharger systems have used a bypass valve connected to the outlet of the compressor to relieve excess pressure. Typically, the bypass valve of these prior art systems sensed the differential pressure between the compressor outlet and inlet ports, i.e., the pressure differential across the throttle valve, and opened the bypass valve to relieve pressure at a given threshold level, with the valve remaining open until the pressure dropped below the threshold level.

Other systems used an exhaust bypass valve between the exhaust manifold outlet and the exhaust system to regulate the turbocharger by redirecting the engine exhaust energy away from the turbine. The exhaust bypass valve of this earlier system was actuated by a valve of the type that sensed the compressor discharge pressure.

Since these systems operated independently and were both either open or closed depending on the compressor discharge pressure, the turbocharger had a very limited efficient operating range. The range was so limited that it was necessary to use different turbocharger hardware, i.e. turbine and compressor wheels, for varying operating altitudes and engine configurations.

Since the turbocharger compressor and turbine wheels are sized not only for altitude, but also to achieve a rated horsepower at a desired speed for each specific engine, the power and torque output of an engine would drop dramatically if the engine was operated at a lower than rated speed or at any other altitude, since the pressure sensing valves were dependent only on the compressor discharge pressure and operated regardless of the engine speed.

For example, an engine rated at 190 psi BMEP (Braking Mean Effective Pressure) at 1000 rpm would struggle to produce 1.3 x 106 Pa (190 psi) BMEP at 700 rpm due to the reduced turbocharger output caused by the decreasing speed and the mechanical pressure sensing and release valves previously used.

Typically, large industrial internal combustion engines operate for long periods and are capable of producing thousands of horsepower. These engines are designed to operate intermittently at 10% above rated load and are used to generate electrical power, pump natural gas and oil, power large ships, operate offshore drilling rigs, etc. In such applications, it is desirable to produce maximum power and/or maintain maximum torque at reduced engine speeds.

However, since previous turbocharger control systems simply functioned in response to compressor discharge pressure, the mechanical valves released pressure regardless of engine speed and therefore independent of engine needs. Under such conditions, when engine speed is reduced but load is maintained, the engine requires a nearly constant intake manifold pressure to maintain output torque.

Under these conditions, it would be desirable to adjust the bypass valve to change the total mass air flow and adjust the exhaust bypass valve to direct more engine exhaust gases to the turbocharger, thereby producing a nearly constant intake manifold pressure so that the supercharger operates more efficiently at these speed and load conditions.

An electronic turbocharger control system for an internal combustion engine, in particular for a stationary engine, which comprises a turbocharger with a turbine and a compressor, a bypass valve connected between the compressor and the turbine to change the air flow through the compressor, an exhaust bypass valve connected between the engine and the turbine to divert engine exhaust gases away from the turbine, an engine characteristic monitor and an electronic control with a processor is known from DE-A-31 29 686.

The present invention provides a simple and effective method and system for maintaining engine torque output at lower than rated speeds and at varying ambient temperatures and barometric pressures by stabilizing turbocharger output within a predetermined range of efficient operation.

Another object of the present invention is to provide an electronic turbocharger control system having an exhaust bypass valve and a bypass valve that eliminates the need to customize individual compressor and turbine wheels of a turbocharger for each specific engine configuration and application.

This particular aspect of the invention allows a manufacturer to use a single set of turbocharger hardware for various engine applications. For example, prior to the present invention, up to 13 different turbocharger wheels were required to adequately cover an altitude range of 0 to 7000 feet above sea level. With the present invention, a single set of turbocharger hardware can be used at all altitudes in this desired range.

Further economic benefits are gained not only from the low cost of the electronic control compared to the high cost of the compressor and turbine wheels, but also from the elimination of inventory and the need for custom-built wheels for special applications. Customer satisfaction can also be greatly improved by eliminating long procurement lead times for replacement components.

Another aspect of the present invention is to provide a constant torque at varying engine speeds, which allows an operator to obtain additional load at reduced engine speeds, thus increasing fuel economy.

Another aspect of the invention is to provide maximum power over a range of engine speeds while still maintaining the turbocharger in its most efficient operating range.

Yet another aspect of the invention is to provide a control system that maintains turbocharger efficiency within a desired range of pressure ratio versus mass air flow rates.

Short description of the drawings

Show it:

Fig. 1 is a schematic representation of a system according to the invention;

Fig. 2 is a schematic representation of a control system according to the invention;

Fig. 3 is a typical graphical representation of a ratio of compressor discharge pressure versus barometric pressure versus mass air flow of a turbocharger compressor;

Fig. 4 is a typical plot of bypass valve position versus intake manifold pressure;

Fig. 5 is a typical graph of exhaust bypass valve position versus intake manifold pressure;

Fig. 6 is a typical graphical representation of the throttle angle position versus the effective mean working pressure.

Detailed description of the preferred embodiment

As shown in Fig. 1, according to the present invention, an engine 10 includes an intake manifold 12 and an exhaust manifold 14 operatively connected to a turbocharger 16. The turbocharger 16 has a compressor 18 and a turbine 20. The inlet of the compressor 18 is connected to an air cleaner (not shown) having an air intake passage 28. The air cleaner filters intake air to atmospheric/barometric pressure that is drawn into the compressor 18 through the air intake passage 28 under a partial vacuum created by a compressor wheel 30 in the compressor 18.

The compressor wheel 30 is driven by a shaft 32 which is driven by a turbine wheel 34 in the turbine 20. The turbine wheel 34 is driven by engine exhaust gases supplied to the turbine 20 through an engine exhaust passage 36 which is connected to the exhaust manifold 14 of the engine 10.

The output of the compressor 18 is connected to an intercooler 22 through a compressor discharge passage 24. The compressor wheel 30 compresses the intake air and causes it to flow through the compressor discharge passage 24 to the intercooler 22, which acts as a heat exchanger removing excess heat from the turbocharged intake air, as is well known.

The turbocharged intake air is then directed to a throttle 38, the intake manifold 12 and to the engine 10. The throttle 38 creates a pressure differential depending on its position such that the air pressure entering the throttle is the compressor discharge pressure and the air pressure exiting the throttle is the intake manifold pressure.

A bypass valve 40 in a bypass passage 42 connects the compressor exhaust passage 24 and the engine exhaust passage 36 to operatively release pressure in the compressor exhaust passage 24 and increase airflow through the compressor 18 by regulating airflow through the bypass passage 42.

An exhaust bypass valve 44 in an exhaust passage 45 connects the engine exhaust passage 36 and an exhaust outlet passage 46 to operatively divert engine exhaust gases into the exhaust passage 36 to thereby reduce the exhaust mass air flow to the turbine 20 so that the compressor discharge pressure generated by the compressor 18 is reduced by regulating the amount of engine exhaust gases through the exhaust passage 45.

A turbocharger control module 48, Fig. 2, has a processor 50 and a memory 52. In the preferred embodiment, the memory 52 is an electrically erasable programmable read only memory (EEPROM) in which the parameters programmed therein can be changed and adjusted in the field. The turbocharger control module 48 has a plurality of engine characteristic signal inputs, namely an intake manifold pressure signal 54, an engine speed signal 56 and an ambient temperature signal 58.

The signals are generated by a variety of engine characteristic monitors, namely, an intake manifold pressure monitor 60 for sensing engine load, an engine speed monitor 62 for sensing engine speed, and an ambient temperature monitor 64 for sensing external temperature. The signals 54, 56 and 58 are fed to the module 48 in analog form and are converted to digital form by an analog-to-digital (A/D) converter 51.

The processor 50 of the turbocharger control module 48 processes the characteristic signals by selecting predetermined values from the memory 52 for the bypass control signal 66 and the exhaust bypass valve control signal 68 based on the values of the characteristic signals and a previously programmed barometric pressure. A digital-to-analog (D/A) converter 53 converts the digital signal generated by the processor 50 into analog signals 66 and 68 in the module 48.

The bypass control actuator 70 senses the bypass control signal 66 and responds by rotating the shaft 72 to change the angular position of the bypass valve 40. Similarly, the exhaust bypass valve control actuator 74 senses the exhaust bypass valve control signal 68 and rotates the shaft 76 to change the angular position of the exhaust bypass valve 44.

The bypass control actuator 70 and the exhaust bypass valve control actuator 74 are electromechanical controls that include a DC motor and drive gear train (not shown) that are well known. The actuators 70 and 74 each include a potentiometer (not shown) to sense the position of the shafts 72 and 76 and to generate a bypass position feedback signal 78 and an exhaust bypass valve position feedback signal 80, respectively.

The turbocharger control module 48 senses the position feedback signals 78 and 80, converts the signals to digital signals in the A/D converter 51, compares the digital signals to the previously determined desired positions of the bypass valve 40 and the exhaust bypass valve 44, generates revised control signals, converts the digital signals to analog signals in the D/A converter 53, and responds with an appropriate bypass control signal 66 and exhaust bypass valve control signal 68 to adjust the bypass valve 40 and the exhaust bypass valve 44 to the desired positions.

The memory 52 of the turbocharger control module 48 is pre-programmed with sets of predetermined parameters reflecting desired settings for the bypass valve 40 and the exhaust bypass valve 44. Each set of parameters is based on engine characteristic signals 54, 56, 58 and an operating system barometric pressure determined for a given altitude.

The present embodiment uses three sets of parameters based on altitude, one for 0-900 m (0-3,000 ft), one for 900 to 1,500 m (3,000-5,000 ft), and one for 1,500 to 2,100 m (5,000-7,000 ft); however, it is within the scope of the invention to vary the number of sets as well as the ranges within each set.

An RS-232 interface 82 provides a service interface for connecting a computer to the turbocharger control module 48, as is well known, to perform initial programming and reprogramming, and to diagnose faults in the module.

The turbocharger control system of the present invention is used on large, industrial internal combustion engines that are typically installed at stationary, immobile assembly sites. Thus, during the initial set-up of a factory, the barometric pressure is calibrated on an absolute basis, and later, when the assembly site elevation is determined, the turbocharger control module is programmed via the RS-232 interface 82 from a barometric pressure monitor 100 to program the processor 50 to select the correct set of pre-programmed parameters from the memory 52 corresponding to the barometric pressure of the engine's working environment.

In this way, the turbocharger 16, Fig. 1, can be controlled to operate within the preferred operating regions shown in Fig. 3 as kidney-shaped curves 102, 104, 106 and 108, also known as efficiency islands.

Fig. 3 shows the ratio of compressor discharge pressure versus barometric pressure versus mass air flow through the turbocharger compressor. Optimum turbocharger compressor output is achieved when the mass air flow and pressure ratio are centered or contained within efficiency islands 102, 104, 106 and 108.

When tested at various engine speeds and loads, it has been found that opening the exhaust bypass valve 44, Fig. 1, reduces the pressure ratio of the vertical axis as shown by exhaust bypass lines 110 in Fig. 3, while opening the bypass valve 40, Fig. 1, increases the pressure sensing air flow of the horizontal axis is increased, but this may also change the pressure ratio of the vertical axis, as shown in Fig. 3 by bypass curves 112.

By testing the system at various engine speeds and loads, an optimal angular position of the exhaust bypass valve 44, Fig. 1, and an optimal angular position of the bypass valve 40 can be determined to control the compressor discharge pressure and mass airflow within the efficiency islands 102, 104, 106 and 108, Fig. 3.

The processor 50, Fig. 2, of the turbocharger control module 48 processes the digital form of the intake manifold pressure signal 54, the engine speed signal 56, and the ambient temperature signal 58, and since it is pre-programmed for the barometric pressure of the operating system's environment, it accesses a look-up table in the memory 52 and generates a bypass control signal 66 and an exhaust bypass valve control signal 68, as previously discussed, which independently control the bypass valve 40 and the exhaust bypass valve 44 to the desired positions to maintain operation within the efficiency islands 102, 104, 106 and 108 of Fig. 3.

The bypass valve 40 shown in Fig. 1 serves two functions. First, since during the engine start-up phase the engine exhaust pressure in the engine exhaust passage 36 is higher than the compressor outlet pressure in the passage 24, the bypass valve 40 is closed to prevent passage of the engine exhaust gases into the compressor outlet passage 24. Second, the bypass valve 40 regulates the compressor outlet pressure and the mass air flow once the engine is running at a minimum idle speed, which is typically 650 to 750 rpm.

Once the minimum engine idle speed is reached, the bypass valve 40 is controlled over a range of effective bypass valve angles. Although the testing in Fig. 3 was conducted over a range of 0º to 80º, Fig. 4 shows that the effective angles are between 0º and 40º. Fig. 4 shows a typical graph of bypass valve angle versus intake manifold pressure for various engine speeds.

As shown, the bypass valve 40 of Figure 1 is held closed until a minimum intake manifold pressure is reached. Once the minimum intake manifold pressure is reached, which in this case is 10⁵ Pa (30 inches of mercury), the bypass valve 40 is set to a predetermined angle in response to the engine characteristic signals.

Similar to bypass valve 40, exhaust bypass valve 44 was tested in the range of 0º to 80º in Fig. 3; however, Fig. 5 shows that the effective angles are between 0º and 35º. Fig. 5 shows a typical plot of exhaust bypass valve angle versus intake manifold pressure for various engine speeds. In its closed state, exhaust bypass valve 44 of Fig. 1 causes nearly all of the engine exhaust gases to flow into turbine 20 and out exhaust outlet conduit 46.

For example, the exhaust bypass valve 44 is closed during initial engine startup to direct all engine exhaust gases through the turbine 20 to drive the turbine wheel 34, which drives the shaft 32 and the compressor wheel 30, until the intake manifold pressure reaches a minimum level, as indicated in Fig. 3 with a pressure ratio between 1.25 and 1.4. Typical effective angle settings for the exhaust bypass valve are shown in Fig. 5 for engine speeds in the range of 750 to 1100 rpm at an exemplary altitude of 650 feet above sea level and an ambient temperature of 37°C (90°F).

Figure 5 illustrates how the invention achieves the desired constant intake manifold pressure as engine speed drops due to changes in exhaust bypass valve angle, resulting in a nearly constant intake manifold pressure, such as shown at data points 122, 124, 126, 128, 130 and 132. By maintaining a substantially constant intake manifold pressure as shown, a substantially constant output torque is achieved.

Functionally, the exhaust bypass valve 44 of Fig. 1 causes increasing portions or amounts of the engine exhaust gases to be diverted to the exhaust outlet channel 46 and to be directed away from the turbine 20 as the angle of the exhaust bypass valve increases, as shown in Fig. 5, so that the speed of the turbine wheel 34, the shaft 32 and the compressor wheel 30 according to Fig. 1 limited to control the compressor discharge pressure as shown by the exhaust bypass valve lines 110 in Fig. 3.

The angles of the bypass valve 40 shown in Fig. 4 and the angles of the exhaust bypass valve 44 shown in Fig. 5 are for illustrative purposes only and may vary depending on the system configuration. For example, an orifice 41, 43 placed in the bypass passage 42 and/or the exhaust bypass valve passage 45 as shown in Fig. 1 allows for a fuller range of effective angles of the exhaust bypass valve and/or the bypass valve and thus reduces any errors resulting from mechanical link tolerances.

Furthermore, the use of different orifice sizes enables the use of the same exhaust bypass valve and/or bypass valve on different engines and applications, further reducing inventory and eliminating long procurement lead times for replacements.

By opening the bypass valve 40 of Fig. 1, the mass air flow through the compressor 18 of the turbocharger 16 is increased, as shown by the bypass curves 112 of Fig. 3, by providing an additional path for the compressor air flow to direct the air flow into the engine exhaust passage 36 of Fig. 1. By opening the exhaust bypass valve 44, the compressor outlet pressure is reduced by directing the engine exhaust gases away from the turbine 20 and directly to the exhaust outlet passage 46.

As shown in Fig. 3 and described above, by simultaneously adjusting the angular position of the bypass valve 40 of Fig. 1 and the exhaust bypass valve 44, the turbocharger 16 can be controlled to operate within the kidney-shaped efficiency islands 102, 104, 106 and 108 of Fig. 3.

The efficiency islands 102, 104, 106 and 108 are common characteristics of centrifugal compressors - the type used in turbochargers - with operation in the center of the islands giving maximum compressor efficiency. It is also known that operation near the peak line 84 of Fig. 3 produces pressure waves between the turbocharger 16 Fig. 1 and the engine 10, resulting in unstable operation which may cause engine damage.

For this reason, a slight safety factor is built into the predetermined parameter so that operation occurs slightly to the right of the center of the islands 102, 104, 106 and 108 of Fig. 3.

In dual bank engine configurations (i.e., V-6, V-8, V-10, V-12, V-16, ...), two turbochargers 16 may be used as shown in Figure 1 to direct turbocharged air through the intercooler 22 to the engine 10. In such an arrangement, a larger bypass valve 40 and a larger exhaust bypass valve 44 may be used.

However, in the present invention, two bypass valves 40 and two exhaust bypass valves 44 are each arranged in the manner shown in Fig. 1 and combined at the intercooler 22. A single control module 48 according to Fig. 2 operates in the manner described above in controlling both bypass valves 40 with a single bypass control actuator 70 and both exhaust bypass valves 44 with a single exhaust bypass valve control actuator 74.

The multiple turbocharger system operates identically to the single turbocharger system, with the exception that the mechanical tolerances between the two compressor wheels and the two turbine wheels must be taken into account.

To compensate for such additional tolerances, it is preferred to operate the turbochargers further to the right of the center of the efficiency islands 102, 104, 106 and 108 as shown in Figure 3 to avoid touching the peak line 84, but remain within an island at all times.

A rightward shift of the efficiency islands 102, 104, 106 and 108 of Fig. 3 is achieved by increasing the mass air flow through the compressor 18 of Fig. 1 by slightly increasing the angular amount by which the bypass valve 40 is opened, as shown by the bypass curves 112 of Fig. 3.

The slight increase in mass airflow through the two turbochargers compensates for any tolerances caused by mismatch between the compressor wheels and/or turbine wheels of the two turbochargers by maintaining a safe distance from the peak line 84, but keeping operation within the efficiency islands. Under certain conditions, the increase in airflow results in a loss in compressor discharge pressure, as illustrated by the bypass curves 112 in Figure 3.

This pressure loss is compensated by reducing the angle through which the exhaust bypass valve 44 is opened as shown in Fig. 1. In other words, a reduction in the exhaust gas flow through the exhaust bypass valve 44 results in an increase in the compressor outlet pressure to thereby compensate for the pressure loss associated with a further opening of the bypass valve 40.

An important requirement in internal combustion engines having carburetors is to maintain a pressure reserve across the throttle 38 of Fig. 1. The pressure reserve can be determined by sensing the pressure on both sides of the throttle 38 and subtracting the two sensed pressures from each other to determine a P which is considered a pressure reserve. The pressure reserve P allows the engine 10 to accommodate larger loads at constant speed or to accelerate at constant load when the throttle 38 is opened without stalling because there is no intake manifold pressure.

However, to achieve optimum engine efficiency, it is desirable to maintain the throttle 38 in an open position to avoid blocking energy in the form of air flow into the engine. The amount of pressure reserve P across the throttle 38 can be regulated by controlling the amount of compressor discharge pressure from the compressor 18. This is accomplished by adjusting the exhaust bypass valve 44 to regulate the amount of engine exhaust gases through the turbine 20, which controls the output of the compressor 18.

By controlling the mass air flow rate through the compressor 30, the throttle 38 can be opened to a larger angle to thereby achieve higher engine efficiency by reducing the exhaust back pressure associated with the higher compressor discharge pressure, but a sufficient pressure reserve P is maintained to accommodate or accelerate additional engine loads without stalling. This increase in throttle angle also reduces energy losses through the throttle, thus increasing engine efficiency.

Another common problem with turbocharged engines that is overcome by the present invention is that the typical non-linear throttle angle profile curve 114 of Figure 6, which is most pronounced in cold climates, is now more linear as shown by curve 116, resulting in improved throttle control. Figure 6 illustrates a plot of throttle angle versus mean effective pressure BMEP for an exemplary engine speed of 1,000 rpm.

Prior to the present invention, as the engine was subjected to increasing loads, such as 0 to 1.45 x 106 Pa (210 psi) BMEP, as shown in Figure 6, the throttle angle had to rapidly increase to compensate for turbocharger lag, an inherent characteristic of turbocharged engines, but once the turbocharger produces sufficient compressor discharge pressure, the throttle angle must rapidly be reduced to create a turning point 118, as shown in Figure 6.

The rapid changes in throttle angle were required to maintain a constant engine speed under increasing compressor discharge pressure. Once the compressor output reaches a plateau, the throttle angle must be reduced to compensate for the increased compressor discharge pressure until the load increase exceeds the increase in turbocharger output, at which point the throttle angle must be increased again to maintain engine speed.

However, this erratic, non-linear throttle angle curve 114 has been extremely difficult to implement with accuracy. The throttle angle is controlled by a monitor (not shown) and in practice compensating for turbocharger output via throttle angle results in erratic engine speeds and speed spikes which are inefficient and undesirable.

An object of the present invention was to achieve stable operation by creating a more linear curve of throttle angle versus load by simultaneously controlling the operation of the bypass valve 40, Fig. 1, and the exhaust bypass valve 44. The throttle angle curve 116 of Fig. 6 is now more linear by adjusting the bypass valve 40 of Fig. 1.

Example bypass (BP) valve angles are shown at test points 120 of Fig. 6 - for example, to achieve a throttle angle curve 116 and pull a load (BMEP) of 0.87 x 10³ Pa (125 psi), a bypass valve angle of 40º (40º BP) results in a throttle angle of about 42º and at a load of 1.2 x 10³ Pa (175 psi), a bypass valve angle of 30º (30º BP) results in a throttle angle of about 46º. However, a byproduct of adjusting the bypass valve 40 is a corresponding change in the pressure reserve P across the throttle 38 of Fig. 1.

Adjusting the exhaust bypass valve 44 in the manner described above results in an adequate pressure reserve P as shown in Fig. 6. At each test point 120, the amount of pressure reserve P is shown in inches of mercury. At lower engine load conditions, larger amounts of pressure reserve 10 are required to allow additional load to be accommodated without stalling.

Opening the exhaust bypass valve 44 results in a reduction in the pressure reserve P. At the upper load end of Figure 6, a decreasing reserve P is preferred because in this case the engine is at or near its rated load capacity and little additional load would be allowed and thus a lower pressure reserve is required to maintain proper engine control and because a lower reserve P provides more efficient operation as described above.

For example, an engine rated at 190 psi BMEP, as in Fig. 6, and a pressure reserve P of approximately 4 to 4.7 x 10⁴ Pa (12 to 14 inches of mercury) is required at 0.87 x 10³ Pa (125 psi) BMEP, while 1.7 to 2.3 x 10⁴ Pa (5 to 7 inches of mercury) is sufficient at 1.45 x 10⁴ Pa (210 psi) BMEP. Similar results can be obtained at various engine speeds, ambient temperatures and barometric pressures.

As shown in Fig. 5, as the engine speed is reduced at constant load (i.e., constant intake manifold pressure), the exhaust bypass valve angle is reduced so that the throttle reserve P is increased and more torque is delivered by the engine at lower speed than previous speed-insensitive systems where there was a loss of intake manifold pressure at lower speeds, resulting in reduced torque output. Fig. 5 discloses efficient exhaust bypass valve angles for each specific engine speed to achieve a desired intake manifold pressure and pressure reserve P.

It is to be recognized that various equivalents, alternatives and modifications are possible within the scope of the appended claims.

Claims (25)

1. Electronic turbocharger control system for an internal combustion engine, in particular for a stationary engine, comprising: - at least one turbocharger (16) connected to the engine (10) and having a turbine (20) and a compressor (18); - at least one engine parameter monitor (60, 62, 64); - an engine characteristic signal (54, 56, 58) generated by the monitor (60, 62, 64); - an electronic control (48) for processing the characteristic signal; - a control signal (66, 68) generated by the processor (48, 50) in dependence on the characteristic signal (54, 56, 58); - a bypass valve (40) connected between the compressor (18) and the turbine (20) to change the air flow through the compressor (18) depending on the control signal (66, 68), and - an exhaust gas bypass valve (44) connected between the engine (10) and the turbine (20) to divert engine exhaust gases (46) away from the turbine (20) in response to the control signal (66, 68), wherein the operation of the turbocharger (16) is graphically represented in a diagram of compressor outlet pressure versus barometric pressure versus turbocharger airflow, the diagram comprising efficiency islands (102, 104, 106, 108) and the electronic controller (48) maintains turbocharger operation within the efficiency islands (102, 104, 106, 108) by controlling the bypass valve (40) and the exhaust bypass valve (44). 2. The control system of claim 1, further comprising a bypass control actuator (70) for generating a response signal (78) indicative of a position of the bypass valve (40), wherein the electronic controller (48) receives the response signal (78) and monitors the position of the bypass valve (40). 3. A control system according to claim 1 or 2, comprising a plurality of engine characteristic monitors (60, 62, 64) to to sense at least the engine speed (62) and the intake manifold pressure (60), and wherein each engine characteristic monitor (60, 62, 64) generates an engine characteristic signal (54, 56, 58) in response to the sense. 4. Control system according to one of claims 1 to 3, wherein the electronic controller (48) has a memory (52) which is programmed with predetermined parameters, the electronic controller (48) selecting a predetermined parameter from the memory (52) and generating the control signal (66, 68) on the basis of the engine characteristic signals (54, 56, 58). 5. A control system according to claim 4, wherein the memory (52) has sets of predetermined parameters, each set based on barometric pressure, and wherein the electronic controller (48) is pre-programmed to select the correct set of predetermined parameters at a given barometric pressure. 6. Control system according to one of claims 1 to 5, wherein the exhaust bypass valve (44) directs at least a portion of the engine exhaust gases (36) into the turbine (20). 7. A control system according to any one of claims 1 to 6, wherein the electronic controller (48) controls the engine exhaust flow to include directing a portion of the engine exhaust (36) into the turbine (20) and directing a portion of the engine exhaust (46) away from the turbine (20). 8. The control system of any one of claims 1 to 7, further comprising an exhaust bypass valve control actuator (74) for generating a response signal (80) indicative of a position of the exhaust bypass valve (44), the electronic controller (48) receiving the response signal (80) and monitoring the position of the exhaust bypass valve (44). 9. Control system according to one of claims 1 to 8, wherein the or an engine characteristic monitor (62) detects the engine speed. 10. Control system according to one of claims 1 to 9, wherein the or an engine characteristic monitor (60) determines the engine load. 11. Control system according to claim 10, wherein the or an engine characteristic monitor (60) senses the pressure in the intake manifold to determine the engine load. 12. Control system according to one of claims 1 to 11, wherein the or an engine characteristic monitor (64) detects the ambient temperature. 13. The control system of any one of claims 1 to 12, further comprising a barometric pressure sensor (100) and wherein the electronic controller (48) is responsive to an engine speed sensor (62), an engine intake manifold pressure sensor (60) and the barometric pressure sensor (100) to control the bypass valve (40) and the exhaust bypass valve (44). 14. The control system of any of claims 1 to 13, further comprising an engine intake throttle (38) disposed between the compressor (18) and the engine (10) and having a throttle angle to variably control the engine intake air, wherein the throttle angle can be graphed against engine load, and wherein the electronic controller (48) enables a substantially linear graph of throttle angle change with changing engine load by controlling the bypass valve (40) and the exhaust bypass valve (44). 15. Control system according to one of claims 1 to 14, wherein the electronic control (48) comprises a processor (50) and a memory (52), wherein the memory (52) is provided with predetermined parameters meters, and wherein the processor (50) selects a predetermined parameter from the memory (52) to control the bypass valve (40) and the exhaust bypass valve (44) in combination. 16. A control system according to any one of claims 1 to 15, wherein the turbocharger (16) has a preferred operating range based on the engine speed (56), the barometric pressure and the intake manifold pressure (54). 17. The control system of claim 16, wherein the electronic controller (48) maintains operation of the turbocharger (16) within the preferred operating range by variably adjusting the bypass valve (40) and the exhaust bypass valve (44). 18. Control system according to one of claims 1 to 17, further comprising: a bypass channel (42) in which the bypass valve (40) and an opening (43) are located, and an exhaust bypass valve channel (45) in which the exhaust bypass valve (44) and an opening (41) are located. 19. Method for controlling the operation of a turbocharger (16) on an internal combustion engine (10), in particular a stationary engine, which uses the system according to claim 1, comprising the following steps: - Obtaining barometric pressure (82, 100) - Obtaining the intake manifold pressure (54, 60); - Maintaining the engine speed (56, 62); - determining a preferred output power of the turbocharger (16) based on the intake manifold pressure (54, 60), the engine speed (54, 60) and the barometric pressure (82, 100); - Regulating the output power of the turbocharger (16) depending on the preferred turbocharger output power and - Regulating the engine exhaust gases (36) to the turbocharger (16) depending on the preferred turbocharger output power, wherein the operation of the turbocharger (16) is graphically represented in a diagram of compressor discharge pressure versus barometric pressure versus turbocharger lift flow, the diagram comprising efficiency islands (102, 104, 106, 108), and the electronic controller (48) maintains turbocharger operation within the efficiency islands (102, 104, 106, 108) by controlling the bypass valve (40) and the exhaust bypass valve (44). 20. The method of claim 19, wherein the step of regulating the output of the turbocharger (16) is further specified to include diverting the output of the turbocharger (16) away from the engine (10) in dependence on the preferred turbocharger output. 21. The method of claim 20, wherein the step of regulating the engine exhaust gases (36) is further specified to comprise diverting the engine exhaust gases (46) away from the turbine (20) of the turbocharger (16) in dependence on the preferred output power of the turbocharger (16). 22. The method of any of claims 19 to 21, further comprising the step of obtaining the ambient temperature (58, 64) and wherein the step of determining a preferred output power of the turbocharger (16) is also based on the ambient temperature (58, 64). 23. The method of any of claims 19 to 22, further comprising: the step of adjusting a particular turbocharger (16) to operate within a preferred operating range for a variety of engine applications based on intake manifold pressure (54, 60), engine speed (56, 62) and barometric pressure (82, 100). 24. A method according to any one of claims 19 to 23, further comprising: the step of adapting a particular Exhaust bypass valve (44) and bypass valve (40) to an engine (10) and a turbocharger (16) based on the size of an opening (41, 43) in a channel (42, 45) connected to the exhaust bypass valve (44) and the bypass valve (40). 25. Stationary internal combustion engine having a control system according to one of claims 1 to 18.